Distention of a joint is often essential in an arthroscopic procedure. This is accomplished by introducing irrigation fluid under pressure into the joint to expand the joint so that it may be worked on more easily and to flush debris from the joint. Conventional techniques accomplish this by elevating a bottle of irrigation solution on a vertically adjustable intravenous infusion stand and connecting a fluid line to a catheter inserted into the joint. Pressure of the flud introduced to the joint can be increased or decreased by raising or lowering the irrigating solution reservoir on the vertically adjustable intravenous stand.
An improvement in the conventional technique is found in U.S. Pat. 4,604,089 which discloses a flow regulation circuit permitting an operator to actuate a first control to elevate the pressure in the irrigation site to a desired level and to maintain the pressure at that desired level when the first control is deactivated. Additionally, the operator may actuate a second control to reduce the pressure at the irrigation site to a base level determined by the height of the reservoir of the irrigation solution and to maintain the pressure at that reduced level when the second control is deactivated.
It would be desirable to have an apparatus which could be used to indirectly and non-invasively regulate and measure the pressure of the fluid in a joint without having to raise or lower a reservoir or operate an elaborate system of valves and flow circuits as disclosed in U.S. Pat. 4,604,089 to provide distention at a joint as well as to provide means for flushing debris from the joint cavity.